This research is aimed at elucidating the molecular mechanisms that control axonal growth and regeneration in the CNS. Second-messenger systems activated by putative growth factor(s) are to be analyzed and such factor(s) purified. The main experimental systems to be used are nerve growth cone fragments (GCPs) isolated from fetal rat brain and cultures of fetal rat cerebral cortex. In the coming year, the following studies will be performed: 1) The further purification and characterization of a peptide factor activating polyphosphoinositide cleavage in CNS growth cones. 2) Analysis of the effects of this putative growth factor on protein phosphorylation in the growth cone. 3) Analysis of the involvement of this peptide factor, of phosphoinositide metabolism, Ca2+, and protein kinase C in the regulation of growth cone motility, using localized application of appropriate agents to neurons sprouting in culture and video-microscopy. 4) Further characterization of membrane protien pp46, a major substrate of a Ca2+/calmodulin-dependent kinase and protein kinase C.